Appeasement

Back in August when I was first getting started with PITCHf/x analysis, I took a quick look at a young and highly-touted rookie who had just broken into the big leagues. Sportvision had not yet brought the PITCHf/x system online at his home park, but we had data from one relief appearance this pitcher made on the road, and I used that to get a quick and dirty read on his pitches.

Oddly enough, that quick analysis has been the source of more search engine hits than any other pitcher analysis on my blog so far. That may have something to do with his team, the New York Yankees. I’m starting to feel like I only write about Red Sox or Yankees around here, and today I’m going to continue pandering to the masses with this update on Joba Chamberlain.

When I looked at Chamberlain’s two-inning appearance in August, he was mainly a fastball-slider pitcher with possibly a couple changeups in that outing, and his fastball was hitting the upper 90’s. With a full season’s data, the basic picture remains the same: upper 90’s fastball, hard-breaking slider. But it looks like he’s relying more on a curveball as an off-speed pitch to lefties, and his changeup has hardly been seen since. In addition, we have enough data to look at usage patterns for his different pitch types and the results he gets from each of them, although that may have to wait until a separate article.

Let’s start by identifying his pitch types. Regular readers will know by now that I like to begin this process by graphing pitch speed versus the direction of the spin axis, which determines the direction the pitch will move due to spin. With some Excel help from Tom Tango, I’m going to try this in a bit different format, one that hopefully makes more intuitive sense to the reader as opposed to the hard-core PITCHf/x researcher. I’m putting the data on a polar plot, showing it from the pitcher’s viewpoint, and graphing the direction of the spin force rather than the direction of the spin axis.

The backspin on a fastball causes it to “rise”, i.e., drop less than a pitch without backspin. The sidespin on a slider makes it break away from a right-handed hitter, and the topspin on a curveball makes it drop more than normal. Hopefully that is clearer from the above polar plot than from the old way I presented this information, which I’ll show below for the sake of comparison (the angles are different).

I’d appreciate feedback on whether the new graphing method is easier to understand or any other comments or suggestions you may have.

Joba Chamberlain’s main pitch is a 95-100 mph fastball, delivered roughly from the 1 o’clock position. His fastball has a little bit of cutting action, moving away from a right-handed hitter more than a typical four-seam fastball, but I wouldn’t say he’s throwing a cutter, as such.

His second pitch is a slider with a lot of break, running 84-89 mph. Some of his sliders look almost like very hard curveballs. He throws the slider more to righties (39% of pitches) than to lefties (26%), but he definitely relies on it to both.

After the two changeups we saw in Joba’s August 10th appearance in Cleveland, the PITCHf/x system only recorded one more, thrown on August 24th to retire Placido Polanco on a fly ball to center field. Those three changeups were thrown around 83 mph. There’s not much else to say about changeups with that small sample.

Upon revisiting Joba Chamberlain, I was surprised to find him using an occasional curveball, mostly to lefties. His curve looks pretty typical, running 77-80 mph.

We can also look at how fast the pitches spin.

What’s impressive about some of those fastballs is that they almost do actually rise–the spin force imparted by 3200 revolutions per minute is almost enough to keep a 99-mph pitch from dropping at all due to gravity. In fact, by my calculations, the rise due to spin came within one inch of counteracting gravity on eight of Joba’s fastballs. That seems impressive to me. I’ve hardly looked at every hard thrower in baseball, and I know J.J. Putz generates some similar numbers, but I don’t think it’s very common.

The other thing to note in this graph is the low spin rate of the slider. In truth, the slider spins much faster, but much of the spin is around the direction of travel (like the spin on a nicely-spiraling football) due to how the slider is thrown. We can’t measure that component of the spin, but fortunately, that’s the component of the spin that also has little effect on how the pitch moves. When I talk about spin rate around here, that’s short hand for the x- and z-components of the spin, that portion of the spin which affects the direction the ball will break. I don’t always mention it, but it bears repeating occasionally. The slower measured “spin” of the slider is often one easy way to differentiate it from a curveball.

Finally, let’s look at the movement on the pitches. This graph shows the movement due to spin (the Magnus force) and gravity, from the perspective of the pitcher.

Joba Chamberlain’s slider really has amazing break and his fastball has a lot of hop. I can see why he is regarded as a special talent.

With that, I’ll sign off for now. Hopefully I can czech in again soon with the next part of this series, and I’m grateful you gave me a piece of your time.

Note: For those of you who are interested in reproducing this sort of analysis for yourself (or finding errors in my math), you can download the Excel spreadsheet that I used.

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3 Responses to “Appeasement”

This is great stuff. In fact, everything you’ve been doing lately is great. I’m a big fan.

I was wondering if you are interesting in reviewing an article idea I am kicking around. I just want you opinion on my idea – pro or con. It deals with how pitchers spin a baseball, and you seem to be the leader in this area.

Mike…nice analysis. One of the interesting things about Joba’s slider is that there is almost no vertical break (i.e., pfx_z, which you did not plot but is in your spreadsheet, is close to 0). That means there is no topspin or backspin component to the spin, only sidespin, as confirmed by your spin direction plot which shows the spin angle around 90-deg (as expected for pure sidespin). Your polar plot also confirms that the break due to the spin is primarily sideways. Now, the really interesting thing is that for the slider, the magnitude of the spin is very small, around 500-1000 rpm. I suspect that what is really going on is that the actual spin magnitude is larger, but that the spin axis is rotated to have a substantial component in the forward (y-axis) direction. As you know, the y component of the spin does not contribute to the movement or break and so is impossible to determine from the trajectory of the pitch.